package mainimport (	"fmt"	"strings"	"time")type Frontmatter struct {	Title     string	Tags      []string	CreatedAt time.Time}func setValue(f *Frontmatter, key string, value string) {	switch strings.ToLower(key) {	case "title":		f.Title = value	case "tags":		tags := strings.Split(value, ",")		for _, tag := range tags {			f.Tags = append(f.Tags, strings.TrimSpace(tag))		}	case "timestamp":		timestamp, err := time.Parse("2-1-2006", value)		if err != nil {			fmt.Printf("Invalid timestamp in post '%s': %s\n", f.Title, err)		} else {			f.CreatedAt = timestamp		}	}}// splits a markdown file into content and frontmatter, removing any whitespace from the former.-------func splitFrontmatter(input string) (content, frontmatter string) {	// the frontmatter content is the middle part	splits := strings.SplitN(input, "---\n", 3)	// no frontmatter	if len(splits) < 2 {		return input, ""	}	frontmatter = splits[1]	content = strings.TrimSpace(splits[2]) // trim leading newline	return content, frontmatter}// returns key:value. feed it ONLY the frontmatter. it doesn't matter if it contains "---" or not.func parseFrontmatter(input string) Frontmatter {	var frontmatter Frontmatter	for line := range strings.Lines(input) {		matches := strings.SplitN(line, ":", 2) // split (but might have a space)		if len(matches) == 2 {			key := strings.ToLower(matches[0])			value := strings.TrimSpace(matches[1])			setValue(&frontmatter, key, value)		}	}	return frontmatter}